/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.hippo4j.config.event;

import java.io.Serializable;
import java.util.concurrent.atomic.AtomicLong;

/**
 * An abstract class for event.
 */
public abstract class AbstractEvent implements Serializable {

    private static final AtomicLong SEQUENCE = new AtomicLong(0);

    private final long sequence = SEQUENCE.getAndIncrement();

    /**
     * Event sequence number, which can be used to handle the sequence of events.
     *
     * @return sequence num, It's best to make sure it's monotone.
     */
    public long sequence() {
        return sequence;
    }
}
